Preparation and characterization of citric acid-modified superparamagnetic iron oxide nanoparticles / 北京大学学报(医学版)

OBJECTIVE@#To prepare and characterize citric acid (CA)-modified super paramagnetic iron oxide nanoparticles (SPIONs) for magnetic targeting, hyperthermia and magnetic resonance imaging (MRI).@*METHODS@#CA-modified SPIONs (CA-SPIONs) were prepared by co-precipitation method and then the magnetic responsiveness, morphology, particle size, infrared feature, weight percentage of CA, magnetic property and X-ray diffraction pattern of CA-SPIONs were respectively characterized by magnet, transmission electron microscope, laser particle size analyzer, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry-differential thermal analyzer, vibrating sample magnetometer and X-ray diffractometer (XRD). The heating efficiency of the CA-SPIONs was investigated by a high frequency induction heater. The transverse relaxivity (r2) of the CA-SPIONs was evaluated by a 3.0 T MRI scanner.@*RESULTS@#The CA-SPIONs prepared were dispersed well in water with a dark black color and had good magnetic responsiveness. The CA-SPIONs were spherical in shape and uniform in size with an average size around 12 nm. The hydrodynamic average size of the CA-SPIONs was (72.35±4.47) nm with a polydispersity index of 0.231 ± 0.029. The result of infrared spectrum indicated that CA was successfully modified to the surface of SPIONs. The result of thermogravimetric analysis showed that the weight percentage of CA modified on the CA-SPIONs was 9.0%. The result of magnetic property evaluation demonstrated that the CA-SPIONs exhibited excellent superparamagetism with a saturation magnetism of 63.58 emu/g. The XRD result indicated that the CA-SPIONs were in inverse spinel structure. The crystallite size of the CA-SPIONs was calculated to be 12.4 nm by Debye-Scherrer equation. Under the high frequency alternating electromagnetic field with electric current of 9 A and frequency ranging from 45 to 50 kHz, the CA-SPIONs exhibited excellent heating efficiency and the specific absorption rate (SAR) value was calculated to be 26 W/g. The r2 of the CA-SPIONs was assessed to be 338 (mmol/L)-1×s-1 by a 3.0 T MRI scanner, which suggested the excellent negative contrast enhancement effect of the CA-SPIONs.@*CONCLUSION@#The CA-SPIONs are expected to be used as a promising agent for magnetic targeting, hyperthermia and MRI detection.

Significance of Diffusion Tensor Imaging of Vastus Medialis Oblique in Recurrent Patellar Dislocation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Numerous studies have investigated the influence of osseous factors on patellofemoral joint instability, but research on the influence of dynamic muscle factors in vivo is still in the exploratory stage. This study aimed to use magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to evaluate vastus medialis oblique (VMO) fiber bundles in patients with recurrent patellar dislocation to explore the changes in muscle morphology and function.</p><p><b>METHODS</b>This prospective study involved 30 patients (7 males and 23 females; average age, 21.4 ± 3.8 years) clinically diagnosed with recurrent patellar dislocation in Peking University Third Hospital and 30 healthy volunteers matched for age, sex, and body mass index in our medical school between January 2014 and October 2014. None of the patients had a recent history of traumatic patellar dislocation or transient patellar dislocation. All patients underwent conventional MRI and DTI of the knee. The cross-sectional area of the VMO on MRI and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and primary (λ1), secondary (λ2), and three-level characteristic (λ3) values on DTI were measured. The independent-samples t-test was used to compare these parameters between the two groups.</p><p><b>RESULTS</b>Compared with the control group, the patient group showed significantly higher FA values (0.39 ± 0.05 vs. 0.33 ± 0.03) and significantly lower ADC (1.51 ± 0.13 vs. 1.58 ± 0.07), λ2 (4.96 ± 0.13 vs. 5.04 ± 0.07), and λ3 values (4.44 ± 0.14 vs. 4.58 ± 0.07; t = 5.99, t = -2.58, t = -3.02, and t = -4.88, respectively; all P < 0.05). Cross-sectional VMO area and λ1 values did not differ between the two groups (t = -1.82 and t = 0.22, respectively; both P > 0.05).</p><p><b>CONCLUSIONS</b>The functional status of the VMO is closely associated with recurrent patellar dislocation. MRI, especially DTI (FA, ADC, λ2, and λ3), can detect early changes in VMO function and might facilitate the noninvasive monitoring of the functional status of the VMO in patients with recurrent patellar dislocation.</p>

Cockayne syndrome / 中国当代儿科杂志

Cockayne syndrome is a rare autosomal recessive disease. This paper reports a case of Cockayne syndrome confirmed by gene analysis. The baby (male, 7 years old) was referred to Peking University Third Hospital with recurrent desquamation, pigmentation and growth and development failure for 6 years, and recurrent dental caries and tooth loss for 2 years. Physical examination showed very low body weight, body length and head circumference, yellow hair, a lot of fawn spots on the face, skin dry and less elastic, and subcutaneous lipopenia. He had an unusual appearance with sunken eyes, sharp nose, sharp mandible, big auricle and dental caries and tooth loss. Crura spasticity and ataxia with excessive tendon reflexion, and ankle movement limitation while bending back were observed. He had slured speech. The level of serum insulin like growth factor I was low, and the results of blood and urinary amino acid analysis suggested malnutrition. The results of blood growth hormone, thyroxin, parathyroxin, liver function, renal function, lipoprotein profile and blood glucose and electrolytes were all within normal limit. An electronic hearing examination showed moderate neural hearing loss. The sonogram of eyes revealed small eye axis and vitreous body opacity of right side. MRI of brain revealed bilateral calcification of basal ganglia and generalized cerebral and cerebellar atrophy, and brainstem and callus were also atrophic. Genetic analysis confirmed with CSA gene mutation. So the boy was definitely diagnosed with Cockayne syndrome. He was discharged because of no effective treatment.

A study on relationship between the contour of articular eminence and traces of the condylar kinematic center and its application in TMD patients / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between the contour of articular eminence and traces of the condylar kinematic center during jaw opening movement in healthy subjects, and compare trace characteristics of condylar kinematic center and MRI findings in TMD patients.</p><p><b>METHODS</b>In 10 healthy subjects, jaw-opening motion was recorded. The kinematic center and terminal hinge axis point of the condyle were used as trace reference points. The contour of articular eminence was examined by MRI. Seven patients with TMD signs and/or symptoms (disk displacement) were selected for this study. The condylar trace was recorded during jaw protrusion and opening-closing. The internal derangement in temporomandibular joints was detected by MRI and defined as: (1). normal disk position, (2). disk displacement with reduction, (3). disk displacement without reduction.</p><p><b>RESULTS</b>In healthy subjects, most of the opening traces of the kinematic center coincided with the contour of articular eminence (8/10 joints in left, 9/10 joints in right). For terminal hinge axis point, no trace coincided with the contour of articular eminence (0/20 joints in left and right). In TMD patients, according to MRI findings, the condylar traces of kinematic center in 3 normal disk position joints showed normal shape. However, in 6 disk displacements with reduction joints and 5 disk displacement without reduction joints, the condylar traces of kinematic center showed irregular patterns except 1 disk displacement with reduction joint.</p><p><b>CONCLUSIONS</b>In comparison with the terminal hinge axis point, the opening traces of the kinematic center can be interpreted as the translatory movement of the condyle/disc along the articular eminence. The study suggests the use of kinematic center in condylar movement studies.</p>

Injuries of anterior glenoid labrum:evaluation with MR arthrography / 中华放射学杂志

Objective To determine the diagnostic value of shoulder MR arthrography in revealing the injuries of anterior glenoid labrum,and to compare MR arthrography with arm in neutral position with MR arthrography with arm in abduction and external rotation(ABER)position.Methods MR arthrography of the shoulder,including additional oblique axial sequences with the patient in the ABER position,was performed in 44 patients.The injuries of anterior glenoid labrum of these patients were retrospectively evaluated.The result was compared with that of arthroscopy.Results For displaying the abnormalities of anterior glenoid labrum,the sensitivity,specificity,and accuracy of axial MR images with arm in neutral position were 79.3%(23/29),100%(15/15),and 86.4%(38/44),respectively.While the results of ABER position oblique axial images were 93.1%(27/29),100%(15/15),and 95.5%(42/44), respectively.The difference of sensitivity between axial and ABER-position scans was statistically significant (P

T_2-mapping of osteoarticular and muscular tissues using turbo spin echo sequence / 中华放射学杂志

0.75).Conclusions The method of single-slice and multi-slice TSE sequence in T_2 measurement is feasible.For bone marrow and extremely long T_2 tissue(for instance,cerebrospinal fluid),however,there may be considerable discrepancy on T_2 values obtained by TSE sequence.

Initial experiences about 16-detector row CT coronary angiography / 中华放射学杂志

70 bpm during scan),the proportion of segments that could not be assessed because of motion artifact were 0.1%(1/759),1.1%(7/649),2.5% (10/407),42.6%(103/242),and 75.5%(108/143),respectively.With conventional selective coronary angiography as the golden standard,the sensitivity,specificity,positive and negative prediction values to detect≥50% stenotic lesions in the assessable segments were 79.2%,96.0%,83.8%,and 94.6%,respectively.There was a significant correlation between the number of segments per patient not assessable because of motion artifact and heart rate during the scan(r=0.655,P=0.000).Conclusion MSCT is capable of achieving high accuracy for detection of coronary artery stenosis,and is a reliable technique to diagnose coronary artery disease.